Great light Mod Mark. A little crude but thats the world of video/photography on a budget.. Keep up the great work.

Rather than actually going to all the work, time and cost of building barndoors for a work light, you could just use some black wrap (also called black foil).  A 50 ft. roll costs less than $25.  It will work just as well as your barndoors, while being lighter, taking only a minute to install and costing less than half as much.  Black wrap is also more rigid than the lightweight aluminum you discuss.  Another benefit of black wrap is that it is malleable and can be shaped into a greater variety of positions than barndoors.  If you aren't overly rough with the black wrap, it is 100% reusable.  It can also be completely removed from the light for increased portability.

You also mention your barndoors will make your lights look more professional.  First of all, it's not the tools you use, but the results you get that make you look professional (Academy award-nominated Rodrigo Prieto, ASC, AMC used strings of Christmas lights taped to a pizza box to create a fire effect in "Lust, Caution").  Second, if you're concerned about "looking professional," if you're using work lights, not even putting barndoors on them will make you look "more professional."  You can put lipstick on a pig, but it's still a pig.  Fortunately, for the image-conscious videomakers out there, black wrap is a professional filmmaking tool and can be found literally on every professional film and TV production.

Nice work Mark, a real class way of giving the worklights a make over.